1. Field of the Invention
The present invention relates to a device, a method and radio-frequency based telecommunication system for short range communication which effects local network access for capacity demanding broadband services in a cellular short range communication system such as, for instance, DECT.
2. Discussion of the Background
Presently, DECT (Digital European Cordless Telecommunications) offers cost efficient local access telephony (e.g., voice) and data communications, where the data communications is not greater than 500 kbit/s. On the other hand, due to capacity limitations, DECT cannot offer broadband services such as, for instance, video-on-demand to a large number of users.
LMDS (Local Multi Point Distribution Services) is another present system that cost efficiently offers distribution of video. LMDS is colloquially known as "wireless cable-TV" and is allocated to frequency bands with a very high capacity, namely, 27.5-29.5 GHz and 40.5-42.5 GHz under the designation MVDS. As recognized by the present inventor, a limitation with LMDS is that it is presently implemented with analog signals and is in its present commercial form does not support Media Access Control (MAC) protocol (or medium access control) for handling of trunked two-way communication. LMDS, however, as anticipated by the present inventor, will in the United States, and probably also in Europe, offer two-way services such as telephony, data and video-on-demand, so development of MAC-protocols and digitization of LMDS will be of great commercial importance. While such development may be going on today in the United States, significant hurdles exist that must be overcome in order to provide profitable systems and to adapt to European standards and conditions.
A problem with existing DECT-systems, as recognized by the present inventor, is that DECT-systems can only transmit narrowband to medium band information, but not necessarily "broadband" information, such as would be needed to support video services.
Presently known systems and publications offer no solutions to the above mentioned problem. For example, example patent documents which have issued in the LMDS-field describe only how to make one-way video distribution possible, but fail to describe MAC-protocols and two-way broadband communication. While prototype high capacity point-to-multipoint systems exist, these prototype systems so far have considerably lower downlink capacity than that which the present inventor has determined is commercially important. Further, common baseband and RF-technologies are utilized in uplink and downlink which implies experimental prototype systems are not exploring the possible benefits associated with using "hybrid" systems.